1. Field of the Invention
The invention relates to belts used on corrugator box-board machines, and more particularly, to an in-line seamed woven belt whereby fabric edges are protected by the addition of polyphenylenesulfide (PPS) or polyetheretherketone (PEEK) yarns.
2. Background of the Invention
On a corrugator box-board machine there is a transformation from sheets of linerboard paper and corrugating medium paper into corrugated box-board. This is achieved by the application of a liquid adhesive to the three sheets of paper and the pressing by one or more corrugator belts, woven or needled or a combination thereof onto a series of steam-heated plates to dry the adhesive thereby “gluing” the paper assembly together. The heat from the plates is conducted directly to the “glued paper” (corrugated box-board) and through this into the corrugator belt.
As well as this drying function, the belt must pass the corrugated box-board through the cooling section and thereafter onto the next stage.
It is generally desirable that corrugator belts possess certain properties such as strength, durability, be dimensionally stable, and have a non-marking seam all under the conditions of high temperature and steam, plus high tension. Additionally, the belts should be flexible in the machine direction yet be sufficiently stable in the cross machine direction so as to maintain close to the belt's original dimensions and facilitate the ability to be guided along its passage around the machine under the conditions described. It is also desirable for the belts to be sufficiently permeable to allow the vapor to pass easily through the material so as not to rewet the corrugated box-board.
Previous corrugator belts had low permeability and utilized the principal of absorption and then evaporation, resulting in the rewetting of the corrugated box-board. This restricted the speed of the corrugator machine because drying was being restricted. These types of belts were typically heavy and very low permeability. The desirable properties had to be achieved by the utilization of a relatively thicker caliper belt composed of spun and multifilament material.
A non-woven type of belt, for example spiral fabrics have also been employed as corrugator belts, but by their nature have problems of mechanical edge damage, for example unravelling and then the unravelled portion being caught on an object within the machine, causing catastrophic failure. Additionally, board slippage resulted due to the slick surface, causing board quality issues and degradation of the fabric edges was caused by the constant exposure to steam, generally by hydrolysis.
The edges of the belt are exposed to more abrasion and heat and hydrolysis degradation as the width of the corrugated box-board changes, which is normal on a corrugator machine. Where there is no corrugated box-board protecting the belt, there is increased abrasion and heat and hydrolysis degradation.
Accordingly, a need exists for a corrugator belt having the ability to survive under the harsh environments longer, by postponing the wear and degradation at the exposed sides of the fabric.